Constant volume feeder for flowable granular material



1965 N. HARTLEY 3,198,386

CONSTANT VOLUME FEEDER FOR FLOWABLE GRANULAR MATERIAL Filed Feb. 8, 1963INVENTOR.

N51. .2, H/ en EY United States Patent 3 198,386 CONSTANT VOLUMli.FEEDER FOR FLOWAEILE GRANULARMATERIAL Nelson Hartley, Baltimore, Md.,assignor to Hartley Controls Corporation, Neenah, Wis., a corporation ofWisconsin FiledFeb. 8, 1963, Ser. No. 257,237 2 Claims. (Cl. 222-55)This invention relates to a constant volume =feeder for fiowablegranular material.

The invention will be described specifically as it is applied to feedingtoundry sand to a continuous sand mixer. The invention is broadlyapplicable, however, wherever a fiowable granular material is to be fedin constant volume from an intermittent source.

In foundries which have batch type mixers supplied from bulk bins, theintermittent and sudden discharge of relatively large quantities of sandfrom the bin to the mixer will ordinarily keep the bin relatively freeof illcrusta tion. However, where continuous mixers are employed and thebin gate is only slightly opened, so as to deliver a relatively smallstream of sand continuously, the sand will tend to rapidly incrustatethe sides of the bulk bin. This problem is accentuated in the typicalfoundry installation where the return sand will vary greatly in bothheat and moisture content.

In practice, a situation will frequently develop where the sidewalls ofthe bulk bin used to supply a continuous mixer will become soincrustated and built up with hard ened foundry sand that the flowopening through the center of the mass of sand in the bin will becomeprogressively smaller until bridged over completely. The mixer must thenbe removed from service and the incrustation mechanically removed atrelatively high cost to the foundry both in labor and lost time.

According to the present invention the continuous mixer is fed aconstant volume of sand, but the bulk bin is only intermittently dumpedto deliver large batches of sand to an intervening hopper from which thesand is metered continuously to the mixer at the proper volume.

This means that the bulk bin cleans itself periodically at a eachdumping operation without substantial opportunity for incrustation todevelop thereon.

Automatic means are provided to refill the hopper when the sand thereinhas dropped to a level below that required to maintain a constant volumedelivery to the mixer.

In practical embodiments of the invention the hopper has an open bottombeneath which a conveyor belt or apron travels. The hopper has a sidewall opening with an adjustable gate to meter the desired volume of sandfrom the hopper as the belt travels therebeneath.

Other objects, features and advantages of the invention will appearfirom the following disclosure in which:

FIGURE 1 is a side view, partly in elevation and partly in section,showing apparatus embodying the present invention.

FIGURE 2 is a simplified circuit diagram of the electrical connectionsfor the apparatus shown in FIGURE 1.

Although the disclosure hereof is detailed and exact to enable thoseskilled in the art to practice the invention, the physical embodimentsherein disclosed merely exemplify the invention which may be embodied inother specific structure. The scope of the invention is defined in theclaims appended hereto.

F-lowable granular material such as foundry sand is supplied to bulk bin10. In the case of foundry sand, some or .most of the sand is returnsand varying in temperature and moisture content.

The sand is mixed with water and various additives to make it suitablefor reuse in the foundry. Such mixing 3,198,386 Fatented Aug. 3, 165

ice

takes place in continuous mixer 11, which requires feeding at a constantvolume. The mixer 11 has substantially a constant volume output.

According to the present invention a hopper 12 is positioned beneath thebulk :bin 10. Hopper '12 has an open bottom disposed over atravelingbelt or apron 13. A side wall of the hopper 12 has an opening14 with an adjustable gate 15. The belt or apron 13 is power driven inthe direction of arrow .16 and will carry granular matetrial :17 fromthe hopper at aum'form depth determined by the adjustment of the gate15. This material is discharged continuously from the belt 13 into themixer 11.

Bulk bin 10 has conventional clam shell gates 20 actuated by the doubleacting tluid motor 21. The fluid lines 22, 23 which supply the motor 21are selectively exposed to the fluid pressure in pipe 24 or to anexhaust pipe 25 through a conventional valve 26 under control of relayor solenoid 27. Relay 27 has plunger 28 connected to operating :arm 19of valve 26 and biased by spring 29 to the valve position shown inFIGURE 2 in which gates 20 are closed.

The level of sand 17 on the belt 13 is sensed by the feeler arm 30mounted from the side wall of the hopper 12 on bracket arm 31. Peelerarm 30 is connected to actuate a switch 32 when the level of material onthe belt 13 drops below that for which the gate 15 is set. When thishappens, on electric circuit to relay 33 is closed, thus to closecontact 41 against the bias of spring 42, energize solenoid 27 and turnvalve 26 to pressurize line 23 and depressurize line 22. Motor 21 willopen clam shell gates 29 and dump or abruptly discharge a batch ofgranular material from the bulk bin 10 into the hopper '12.

A holding circuit to relay 33 will also be established through contact43. This circuit is completed through upper hopper switch 35 which isclosed for lack of pressure on paddle 34. The hopper will rapidly fill.Switch 32 will open as soon as the level of sand '17 on belt 13 isrestored, but the holding circuit through contact 43 keeps gates 20open. As soon as the level of granular material in hopper 1-2 rises tothe point where it lifts paddle 34, switch 35 .will open to break theholding circuit to relay 33 and spring 42 will open both contacts 41, 43to deenergize solenoid 27. Spring 29 will then restore valve 26 to itsposition shown in FIGURE 2 to pressurize line 22 and depressurize line23. Motor 21 will then close the clam shell gates 20.

Material 17 will continue to be conveyed in constant volume from thehopper 12 until its level again drops to the point at which switch 32 isactuated, thus to dump or abruptly discharge another batch of materialfrom the bin 10 into the hopper 12. Bin 10 will be self-cleaned becauseof the sudden out-rush of sand or like flowable granular materialtherefrom at spaced intervals.

I prefer to provide the bin 10 with a deflector plate 37 which has anarea substantially about double that of the bin gate outlet and whichmay be mounted in the bin on cross channel "support beams 38. As analternative the deflector 37 may. be suspended from the top of the binon chains. In any event, the deflector 37 requires the material in thebin to flow along and scour the side walls of the bin. This furtherprevents incrustation of the bin side walls and reduces the need forcleaning.

I claim:

1. Apparatus for treating foundry sand and like flowable granularmaterial, said apparatus including -a bulk bin having side walls whichtend to become incrusted by the granular material and from which thegranular material is periodically dumped in batches to rush out of saidbin, a continuous mixer having a substantially continuous constantvolume demand for granular material and feeding mechanism adapted toreceive the granular material from the bulk bin in batches and tofurnish said material to said apparatus at a constant volume level, saidfeeding mechanism comprising:

(a) hopper into which said bin discharges,

(b) conveyor beneath said hopper for carrying material away from saidhopper at :a constant volume level,

() first sensing means to detect when the hopper is empty,

((1) second sensing means to detect when the hopper is full,

(e) gate means on the bin,

(i) means for widely opening said gate means to dump a batch of materialfrom the bin into the hopper in response to said first sensing means andto close said gate means in response to said second sensing means,

(g) said gate means comprising means for opening the bin wide enough tocause the flowable granular material therein to be abruptly dischargedand scour the side walls of the bin and prevent incrustat-ion thereof.

2. The device of claim 1 in which said conveyor cornprises an apron,said hopper having an open bottom beneath which said apron is disposedand aside .Wall having an opening and an adjustable gate over saidopening to 5 regulate the depth of material carried away from the hopperby the :apron.

References Cited by the Examiner- UNITED STATES PATENTS 1,460,573 7/23Church at al 222-55 X 2,542,239 2/51 Engels et al 222-76 X 2,637,4345/53 Harper et a1. 22255 X 3,072,295 1/63 Lorette 222503 X FOREIGNPATENTS 801,304 9/58 Great Britain.

EVERETT W. KIRBY, Primary Examiner.

LOUIS J. DEMBO, Examiner.

1. APPARATUS FOR TREATING FOUNDRY SAND AND LIKE FLOWABLE GRANULARMATERIAL, SAID APPARATUS INCLUDING A BULK BIN HAVING SIDE WALLS WHICHTEND TO BECOME INCRUSTED BY THE GRANULAR MATERIAL AND FROM WHICH THEGRANULAR MATERIAL IS PERIODICALLY DUMPED IN BATCHES TO RUSH OUT OF SAIDBIN, A CONTINUOUS MIXER HAVING A SUBSTANTIALLY CONTINUOUS CONSTANTVOLUME DEMAND FOR GRANULAR MATERIAL AND FEEDING MECHANISM ADAPTED TORECEIVE THE GRANULAR MATERIAL FROM THE BULK BIN IN BATCHES AND TOFURNISH SAID MATERIAL TO SAID APPARATUS AT A CONSTANT VOLUME LEVEL, SAIDFEEDING MECHANISM COMPRISING: (A) HOPPER INTO WHICH SAID BIN DISCHARGES,(B) CONVEYOR BENEATH SAID HOPPER FOR CARRYING MATERIAL AWAY FROM SAIDHOPPER AT A CONSTANT VOLUME LEVEL, (C) FIRST SENSING MEANS TO DETECTWHEN THE HOPPER IS EMPTY, (D) SECOND SENSING MEANS TO DETECT WHEN THEHOPPER IS FULL, (E) GATE MEANS ON THE BIN, (F) MEANS FOR WIDELY OPENINGSAID GATE MEANS TO DUMP A BATCH OF MATERIAL FROM THE BIN INTO THE HOPPERIN RESPONSE TO SAID FIRST SENSING MEANS AND TO CLOSE SAID GATE MEANS INRESPONSE TO SAID SECOND SENSING MEANS, (G) SAID GATE MEANS COMPRISINGMEANS FOR OPENING THE BIN WIDE ENOUGH TO CAUSE THE FLOWABLE GRANULARMATERIAL THEREIN TO BE ABRUPTLY DISCHARGED AND SCOUR THE SIDE WALLS OFTHE BIN AND PREVENT INCRUSTATION THEREOF.